Properties of a Cl- conductive pathway(s) in microsomes from rat kidney inner medulla - Involvement of cystic fibrosis transmembrane regulator protein

The properties of a protein-kinase-A(PKA)-activated Cl--conductive pathway(s) in alkaline phosphatase-enriched microsomes from the rat inner medulla (IMV) were investigated. Transcripts of cystic fibrosis transmembrane regulator (CFTR) were detected by reverse transcription/polymerase analysis of total RNA from the inner medullar while immunoblot analysis using anti-CFTR antibodies detected a 170-kDa protein in the IMV. The PKA Cl--conductive pathway(s) was studied by measuring the rate of valinomycin-induced microsomal swelling by light scattering, PKA increased the rate of valinomycin-induced swelling of vesicles consistent with the presence of Cl--conductive pathway(s). The pharmacological properties and anion selectivity of the PKA-activated Cl--conductive pathway(s) were similar to those of the CFTR Cl- channel. Our results show that a CFTR Cl- channel and possibly another cAMP-activated pathway(s) may participate in Cl- secretion in the rat inner medulla.